1. Field of the Invention
This disclosure relates generally to networking systems and, more particularly, to a system for intelligent management of node quorum role settings.
2. Description of Related Art
Computer clusters are groups of interconnected computers (“nodes”) associated in such a way as to facilitate interoperability and management. The nodes in a cluster work in tandem to provide superior performance and availability than that of a single computer. The nodes of a high availability cluster have redundant configurations so that any node in the cluster can seamlessly replace a failing node. A cluster configuration database may contain information about the role and status of each node. For example, some nodes may be active, while other nodes may be in standby. The configuration database may be stored on a network drive, which is shared among the nodes. Another approach is to store a copy of the database in each node of the cluster.
Currently, cluster-managing software allows a cluster's configuration to be changed when a “configuration quorum” of the total number of nodes can participate in making that change. A quorum may be equal to the total number of nodes in the cluster (“N”) divided by two plus one (“N/2+1”). Given a cluster startup requirement that at least half the cluster nodes be available at startup time, these nodes guarantee to represent the latest, most accurate configuration of the entire cluster since all combinations of half the nodes will include at least one node with the latest version of configuration information.
Similarly, a cluster manager can permit access to critical cluster resources to nodes of an “operational quorum.” The nodes of an operational quorum are greater than or equal to a simple majority. In a network-sundered situation the nodes belonging to the operational quorum will be permitted access to the cluster's critical resources. If there is an even number of nodes (and thus half the number of nodes is a tie), a deterministic tiebreaker mechanism can be executed that selects only one set of sundered sets of nodes as having operational quorum.
It is desirable to provide an intelligent means of managing node-specific roles so that a subset of all nodes may determine the quorum characteristics of the entire cluster. It would also be desirable for subsystems (e.g., non-interactive programs running on the nodes, such as daemons) to be able to utilize a quorum strategy to ensure their own configuration integrity. Current systems and methods do not facilitate coordination of node quorum roles between clusters and their respective subsystems.